Abstract 5251: Anergic response of NK cells mediated by killer cell lectin-like receptor C1 and tumoral HLA-E interaction in pleural metastasis of lung adenocarcinoma

Abstract The presence of effusion is negatively correlated with prognosis in lung cancer. Despite the advent of novel therapies, clinical outcomes remain unsatisfactory. Pleural metastasis and malignant pleural effusion (MPE) result from tumor-host interactions involving mechanisms such as pleural inflammation, angiogenesis, and vascular hyperpermeability. Natural killer (NK) cells are potent immune effectors capable of responding to cancer. However, several aspects of NK cell biology remain under investigation. Understanding their role will aid in identifying effective therapeutic targets. Effusion samples from patients with congestive heart failure (designated as HP) and lung cancer pleural metastasis (LCP) were collected. Cells were harvested to delineate the functional phenotype of NK cells using single-cell RNA sequencing (scRNA-seq). Additionally, changes in NK cells were validated using immunohistochemistry and cell marker identification. The results revealed six subsets of NK cells: CD16+/CD56- NK cells, CD16-/CD56+/XCL2+ NK cells, CD16-/CD56+/RUNX2+ NK cells, CD16+/CD56+/BCL11B+ NK cells, CD16+/CD56+/CCL3+ NK cells, and CD16-/CD56- NK cells. Most NK cell subclusters dominated in the LCP group, except for CD16+/CD56- NK cells, which were prevalent in the HP group. These NK cell subsets exhibited different expression patterns of inhibitory receptors (KLRC1 and KLRD1) and activating receptors (HCST and KLRK1). Notably, CD16-/CD56+/RUNX2+ NK cells were present exclusively in MPE and absent in effusions from HP. Compared to other NK cell subsets, CD16-/CD56+/RUNX2+ NK cells exhibited lower expression of activating receptors and higher expression of inhibitory receptors, particularly KLRC1, suggesting an immunosuppressive phenotype. Cell-cell interaction analysis using CellChat indicated that HLA-E in pleural tumors interacted with RUNX2+/CD16-/CD56+ NK cells, resulting in decreased NK cytotoxicity. This interaction was further validated through higher expression of HLA-E in pleural tumor cells by immunohistochemistry and the presence of CD16-/CD56+/RUNX2+ NK cells in malignant effusions of lung cancer by a flow cytometry. These findings imply that the presence of the inhibitory ligand HLA-E from tumor cells supports the formation of pleural metastasis by evading NK cell-mediated cytotoxicity. Further investigation into these cell groups may aid in the prevention and treatment of MPE in lung cancer. Citation Format: Ying-Ming Tsai, Kuan-Li Wu, Ya-Ling Hsu. Anergic response of NK cells mediated by killer cell lectin-like receptor C1 and tumoral HLA-E interaction in pleural metastasis of lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5251.